Regenerated cellulose filaments

ABSTRACT

Novel alkali resistant cellulose regenerated filament having a new fibrillary arrangement different from that of other alkali resistant cellulose regenerated filaments, characterized by a crossed position of the fibrils constituting the filament, having an orientation angle of about 35* to about 47* and an organization degree of from about 0.42 to about 0.48; in addition this invention related to an alkali resistant regenerated cellulose filament having a conditioned tenacity of about 3.5 to 7 g/den., a conditioned elongation of about 30-14 percent, a wet tenacity of about 2.7-6 g/den. a wet elongation of about 40-16 percent, a work product in the conditioned state of about 70 to about 115 and a work product in the wet state of about 70 to about 115; further, this invention relates to alkali resistant regenerated cellulose filaments having a loop tenacity of about 1.2 to about 2.1 g/den., a water filtration number of about 3 to about 10 and a dyeing index of about 1.15. In addition this invention relates to the corresponding acetylated cellulose filaments.

United States Patent 1 1 1111 3,875,141

Drisch Apr. 1, 1975 REGENERATED CELLULOSE FILAMENTS Inventor: Nicolas 11. mm, Paris, France 5 7 55 5 3fg' m g i gi g [73] Assignee: Chi o ex, SA" G Attorney, Agent. or FirmSherman & Shalloway Switzerland [22] Filed: Aug. 26, 1968 [57] ABSTRACT [2]] Appl. No.: 778,877 Novel alkali resistant cellulose regenerated filament having a new fibrillary arrangement different from 60 ,Rehted Apphcatlon Data that of other alkali resistant cellulose regenerated fila- 5)r4v31's21ofin8gfSe|1;. 1:0. 796.(? F0l i 1 1P? merits, characterized by a crossed position of the fi- Nos 595 glov I TEJ Sb Zn dEEES Z 2: brils constituting the filament, having an orientation 16 Ml1y i abandoned angle of about to about 47 and an organization degree of from about 0.42 to about 0.48; in addition [52] Us. Cl 260,212 8/121 8/l82 this invention related to an alkali resistant regenerated 264/188 264/194 2647195 264/l96 cellulose filament having a conditioned tenacity of 264/l97' 260/227 260/229 about 3.5 to 7 g/den., a conditioned elongation of 1511 Int. Cl. 006m 13/211,15018 3/28 30-14 a tenacity of about 158 1 Field of Search 264/188, 198, 195, 196, a -16 Percent 264H97. 260/212 227 8/] 163 121 work product in the conditioned state of about to i i i about US and a work product in the wet state of [56] References Cited about 70 to about further, this invention relates to alkali resistant regenerated cellulose filaments hav- UNITED STATES PATENTS ing a loop tenacity of about 1.2 to about 2.1 g/de11.. 11 5607955 3/1953 Drlsch 364/193 water filtration number of about 3 to about l0 and a dyeing index of about [.15. In addition this invention :'l:3 l4:2l6 6 1967 lnoshita chill III: 1:: 564 197 relates to Corresponding acetylated Cellulose 3.341.645 9/1967 HOliuChi ct al 264/197 mems 3.432.589 3/1969 Drisch r r 264/l97 3.539.679 11/19711 Kimura 266/197 5 Clams 9 Draw figures PAIENIEII N975 1875.141

mm 1 u; 3

VISCOSE COAGULATING BATH GEL FILAMENTS (GAMMA-INDEX 45) FIRST STRETCHING 0F 30-80 IN AIR AND EXTRACTION OF PART OF THE LIQUID IM- PREGNATING THE GEL FILAMENTS GEL FILAMENTS HAVING A GAMMA-INDEX 0F 28-40, A DEGREE 0F SWELLING 0F 5-8, AND AN ACID CONTENT (IN THE IMPREG- NATING LIQUID) 0F 6-9, 5g/LITER SECOND-'STRETCHING 0F O-I0O% IN AIR. AFTER STRETCHING GAMMA-INDEX IS COMPRISED BETWEEN I8 AND 28 RELAXATION 8-2070 IN DILUTED ACID BATH REGENERATION MENTOR NICOLAS DRISCH FIG. 1

ATTORNEY PATENIEUAPR 1 I915 SHEET 2 BF 8 (B) GROUP II (FILAMENT C) (A) GROUP 1 (FILAMENT A) (C') GROUP 11! (FILAMENT E) "55m invention (0 GROUP 111 (FXLAMENT o) PRESENT INVENTION (D) COTTON (C' GROUP III FILAMENT F) IIQILLAR PRESENT INVENTION mar-mam PATENIEU 1875.141

SHEET 3 BF 8 GROUP 1 GROUP 11 CFILAMENT A) (FILAMENT c) GROUP III GROUP II! (FILAMENT o) (FILAMENT E) PRESENT mvermou "55m mvznnou FI;G.3

X-RAY OIAGRANS (SHOWING ORIENTATION ANGLE) GROUP "I (FILAMENT F) PRESENT INVENTION SHIU u {IF 8 mu Wm INVENI OR NICOLAS DRISCH ATTORNEY w QE TENACITY g/DENIER IIIENIED APR I I975 TENACITY g/DEN IIZET S [If FILAMENT A (GROUP 1) FILAMENT D 7 (PRESENT INVENTION) (GROUP 111) FILAMENT C (GROUP I[ 5 IMPROVED) FILAMENT E (PRESENT INVENTION) 4 (GROUP m) FILAMENT F (PRESENT INVENTION) 2 (GROUP 111) FILAMENT B (GROUPIL NORMAL) I I I I I I 5 IO )5 2o 25 30 ELONGATION,

FIG. 5 0 LOAD-ELONGATION CURVES DRY STATE FILAMENT A (GROUP 1) FILAMENT D PRE ENT INVENTI N gs oap o FlLAMENT E (PRESENT INVENTION) FILAMENT c (GROUP (GROUP Il IMPROVED) FILAMENT F (PRESENT INVENTION) (GROUP III) FILAMENT B (GROUPH NQRMAL) l i I ELONGATION /o INVENTOR 5 b N|COLAS DRISCH LOAD'ELONGATION CURVES WET STATE di- EZ l ATTORNEY PATENTED APR 1 I975 SHEET 7 BF 8 GROUP 1 (FILAMENT A) A 35 MINUTES A ll MINUTES cnour u (FILAMENT G) I II MINUTES I 3 MINUTES GROUP III (FILAMENT D) PRESENT INVENTION C' u MIMITES C IS MINUTES cnouw n1 (FILAMENT E) "55m INVENTION D' 35 MINUTES 0 ll MINUTES GROUP In (FILAMENT F) PRESENT INVENTION 35 MINUTES E II MINUTES FIG.7

FIBRILLATION REGENERATED CELLULOSE FILAMENTS The present application is a division of application Ser. No. 706,030, now US. Pat. No. 3,432,589, which in turn is a continuation-in-part of application Ser. No. 595,563 filed Nov. 15, 1966 and now abandoned, and of application Ser. No. 637,986 filed May 12, 1967 and now abandoned.

The present invention relates to novel regenerated cellulose filaments and to a novel viscose spinning process for their manufacture. More particularly, this invention relates to novel alkali resistant regenerated cellulose filaments, fibers, threads and yarns and to a process for their manufacture, said filaments having outstanding and unexpected properties, in particular the following properties:

a. a new fibrillary arrangement different from that of the other artificial fibers, and characterized by a crossed" position of the fibrils constituting the filaments;

b. relatively high tenacity together with relatively high elongation;

c. an exceptional energy level (to be defined hereinafter) and consequently a very high toughness;

d. excellent transverse strength which is expressed by a high loop resistance and characterized by a high resistance to fibrillation.

Conventionally alkali resistant regenerated cellulose filaments are obtained, as is well known, by spinning viscoses which possess a high gamma index and viscosity, and which contain a high DP cellulose, into cold baths having a low acid concentration. The formed filaments may be stretched in air and/or in the first bath, and they are then regenerated in a second hot diluted acid bath. The filaments obtained according to processes of the type described have advantageous properties in comparison with ordinary regenerated cellulose filaments. The alkali resistant regenerated cellulose filaments have conditioned and wet tenacities that are much superior to those of ordinary rayons. The ratio of wet-conditioned tenacities of the presently known regenerated cellulose filaments of this type attain 75 to 80 percent. These filaments have a high modulus of elasticity in the wet state which imparts to the corresponding fabrics an excellent dimensional stability. In addition, the filaments have a very characteristic microfibrillar structure, which is only slightly affected by 5 percent caustic soda solutions whereas ordinary textile rayons and high tenacity rayon tire yarns treated with a 5 percent soda solution under the same conditions become greatly damaged.

More specifically, the termalkali resistant" as used throughout the present disclosure relates to regenerated cellulose filaments which after treatment with a 5 percent caustic soda solution at 20C for minutes, followed by rinsing and complete neutralization, have an elongation in the wet state lower than 8 percent under a load of 0.5 g/den. This elongation is measured on a single filament and in fact represents a modulus of elasticity.

In addition, the term "filament" which is widely used throughout the present disclosure means not only filaments" but equally fibres," and other shaped structures obtained from viscose.

All the characteristics enumerated above impart to the finished articles made from alkali resistant regenerated cellulose filaments remarkable properties, in particular, dimensional stability through repeated laundering, mercerization resistance, and a better than average ability to take up resin finishing treatments.

The compared characteristics of alkali resistant regenerated cellulose filaments, high-tenacity rayons for industrial applications, and ordinary textile rayons have been described in numerous articles in the literature, for example, in Reyon Zellwolle 1959, v. 7, pp. 43l-436, and Svonsk Peperstindning 1962, v. 4, pp. l 18-! 2| These articles disclose differences that distinguish alkali resistant regenerated cellulose filaments from the usual or ordinary regenerated cellulose filaments. In fact, alkali resistant regenerated cellulose filaments are closer in structure to cotton then to the usual, or ordinary rayons.

A large number of processes are known for the manufacture of alkali resistant regenerated cellulose filaments. Duringthe first period of development that extended from 1943 to [959, a certain number of pioneer parents were granted. However, in spite of their advantageous properties, filaments produced in accordance with the prior art techings still have tenacity and elongation properties that are relatively inadequate for the present day requirements of the textile industry, and they also present low loop and knot strengths. Therefore, especially since 1960, new processes have been developed that make it possible to improve the longitudinal properties of these filaments without sacrifice of the transverse properties. As an alternative these processes have made it possible to obtain higher loop tenacities and greater elongation without any loss of the initial tenacity characteristics.

The filaments obtained according to the most recent of these processes generally have higher tenacities, but their elongations are substantially the same, and their transverse properties have not been substantially improved. Some of the most recent processes are based on the addition of formaldehyde to the viscose immediately prior to spinning, or to the dilute spinning bath, in order to obtain stable xanthate complexes and to be able to increase the stretching and orientation of the filaments in the gelled state. It is well known by skilled workers in this art that spinning in the presence of formaldehyde entails some very serious difficulties and consequently these prior art processes are not successfully exploited commercially. Furthermore, the prior art processes often involve a very high axial orientation and it is necessary to utilize swelling treatments in intermediate baths in the course of spinning, or after spinning, to improve the transverse resistance of the filaments. The swelling treatments are carried out with solutions of caustic soda, or other alkaline agents and they have the disadvantage of yielding irregular results, thereby seriously complicating industrial production of alkali resistant regenerated cellulose filaments.

If the mechanical characteristics of the filaments of the alkali resistant type described and produced in the prior art are examined, it is observed that the filaments can be classified into the following two groups:

Group I Filaments with very high tenacity and a low-breaking elongation These filaments are generally obtained according to processes in which the spinning is effected in the presence of formaldehyde and they have conditioned tenacities of from about 4 to about 10 g/den. with conditioned elongations of from 8 to 4 percent. Said filaments have an excess of tenacity that serves no purpose, but on the other hand, they have an insufficient elongation. In addition, they have low loop resistance and they readily fibrillate.

When these filaments are examined by the conventional X-ray techniques, it is observed that they have a low orientation angle (the crystallites are highly oriented in relation to the axis of the filaments) and a high degree of organization.

Group II Filaments which have relatively low tenacity and relatively high breaking elongation That is, these filaments have conditioned tenacities from 3.5 to 4.5 g/den. and corresponding elongations of l3 to l 1 percent. In this second group, there are also the so-called improved" filaments which have higher tenacities without loss of elongation, said filaments having a conditioned tenacity of from to 5.5 g/den., and their elongation remaining substantially the same. This entire group, therefore, comprises filaments having a conditioned tenacity ranging from 3.5 to 5.5 g/den. and a conditioned elongation of 13 to II percent. Their transverse strength, although better than that of filaments of the first group, is nevertheless not satisfactory for commercial textile purposes for producing fabrics of good overall performance with respect to their wearing characteristics.

When these filaments are examined by conventional X-ray techniques, it is observed that they have a higher orientation angle (the crystallites are less oriented in relation to the axis of the filaments) and a much lower degree of organization.

In accordance with the novel and unobvious method which will be described hereinafter there are obtained the novel alkali resistance regenerated cellulose filaments of the present invention, which filaments possess outstanding and unexpected properties not heretofore available in the regenerated cellulose filaments of the prior art such as those illustrated in Groups I and II.

Therefore, it is a primary object of the present invention to provide a novel and unobvious third group of alkali resistant regenerated cellulose filaments and a method for their manufacture, wherein said filaments have an orientation angle of about 35 to about 47 and an organization degree of from about 0.42 to about 0.48.

It is a further object of the present invention to provide novel and unobvious alkali resistant regenerated cellulose filaments and a method for their manufacture, wherein said filaments have an entirely new structure characterized by a crossed position of the fibrils relative to the axis of the filament.

Still a further primary object of the present invention is to provide novel and unobvious alkali resistant regenerated cellulose filaments and a method for their manufacture, wherein said filaments have a conditioned tenacity of about 3.5-7 g/den., a conditioned elongation of about l4 percent, a work product in the dry state of about 70 to about l 15, and a work product in the wet state equally of about 70 to about I15.

A further object of the present invention is to provide novel and unobvious alkali resistant regenerated cellulose filaments and a method for their manufacture, wherein said filaments have in addition to a dry elongation of 30l4 percent, and to a wet elongation of 40-16 percent, a dry loop tenacity of about L2 to about 2.1 g/den.

Another object of the present invention is to provide novel and unobvious alkali resistant regenerated cellulose filaments and a method for their manufacture, said filaments being substantially non-fibrillatable and having a water filtration number of about 3 to about 10.

Still another object of the present invention is to provide novel and unobvious alkali resistant regenerated cellulose filaments and a method for their manufacture wherein said filaments have a dyeing index of about 1.15.

It is still a further object of the present invention to provide an acetylated cellulose filament having a conditioned tenacity of about 3 to 5 g/den., a wet tenacity of about 2.3 to 3.6 g/den., a conditioned elongation of about 27 to l4 percent, a wet elongation of about 38 to I7 percent, a wet modulus of about L6 to 0.6 percent, and a conditioned loop tenacity of about 1.9 to 0.8 g/den.

It is still a further object of the present invention to provide a fabric formed of the novel regenerated cellulose filament of the subject invention.

Still another object of the present invention is to provide a resin finished fabric wherein said fabric is formed of the novel regenerated cellulose filaments of the present invention.

Still another object of this present invention is to provide a fabric formed of the novel acetylated cellulose filaments of the present invention.

Other objects and advantages of this invention will be apparent from the following description.

To illustrate the unexpected nature of the novel regenerated cellulose filaments of the present invention, reference is hereby made to FIGS. 1, 2, 3, 4, 5, 6, 7 and 8 wherein all filaments of Groups I, II and III belong to the alkali resistant type.

FIG. 1 is a flow sheet schematically illustrative of the novel and unobvious process of the present invention for preparing the novel alkali resistant filaments described herein.

FIG. 2 (A) illustrates the structure of an ordinary, highly oriented regenerated cellulose filament of Group I (filament A).

FIG. 2 (B) illustrates the structure of an improved regenerated cellulose filament of Group II (Filament C).

FIG. 2 (C) illustrates the entirely new structure of a filament of Group III of the present invention (Filament D).

FIG. 2 ((3') illustrates also the new structure of another filament of the present invention, Group III (Filament E).

FIG. 2 (C") illustrates also the new structure of another filament of the present invention, Group III (Filament F).

FIG. 2 (D) illustrates the structure of cotton.

FIG. 3 represents X-ray diagrams showing the diffraction arcs of filament A of Group I (highly orientated regenerated cellulose filament), of filament C of Group II (improved regenerated cellulose filament), and of filaments D, E and F of Groups III (the novel regenerated cellulose filaments of the present invention.)

FIG. 4 represents the curves of intensity obtained at different angles with an X-ray goniometer, showing the organization degree for filament A of Group I, filament C of Group II and filament D of Group III.

FIG. 5a and FIG. 5b are tenacity-elongation curves respectively in the conditioned and in the wet states, illustrating the advantages of the alkali resistant regenerated cellulose filaments D, E and F of the present invention over those alkali resistant regenerated cellulose filaments A, B and C produced in the prior art.

FIG. 6 illustrates the wet modulus of the filaments produced in the prior art (Groups I and II), of the filaments D, F and G of the invention (Group III), and of other different types of cellulose regenerated filaments, after treatment of all these filaments with a 5 percent caustic soda solution.

FIGS. 7 A and A illustrate that with known regenerated cellulose filaments of Group I, numerous fibrils are formed after 18 and 36 minutes of vigorous beating in a mixer.

FIGS. 7 B and B illustrate that with known regenerated cellulose filaments of Group II, still numerous fibrils are formed after 18 and 36 minutes of vigorous beating in a mixer.

FIGS. 7 (C) and (C') illustrate the beginning fibrillation of the alkali resistant regenerated cellulose filaments D of the present invention after 18 minutes of vigorous beating in a mixer, as well as fibrillation of the filaments after 36 minutes of vigorous beating in a mixer.

FIGS. 7 (D) and (D') and FIG. 7 (E) and (E') illustrate that there is practically no fibrillation with filaments E and F after l8 and 36 minutes of vigorous beating in a mixer.

FIG. 8 is a chart illustrating the different properties of fabrics prepared from the regenerated cellulose filaments of the Groups I, II, III and cotton wherein the same have been given a wash and wear finishing treatment.

Turning now more specifically to FIGS. 2 (A), 2 (B), 2 (C), 2 (C'), 2 (C") and 2 (D) wherein the novel alkali resistant filaments of the present invention are compared with the prior art filaments, FIG. 2 (A) shows that for the ordinary highly oriented filament A of Group I, the fibrils are substantially parallel and closely packed against one another, and this structure is responsible for low elongation, low modulus of elasticity, low work to rupture, high tendency to filbrillation, etc,

FIG. 2 (B) shows that for filament C of Group II the fibrils are not in a substantial parallel relationship and are irregularly arranged over the whole cross section of the filament.

FIGS. 2 (C), 2 (C') and 2 (C") show the new structure of the alkali resistant filaments D, E and F of Group III of the present invention, and, in particular the crossed position of the fibrils relative to the axis of the filaments. This structure is characterized by an assemblage of perfectly well defined fibrils which are regularly arranged over the whole cross section of the filaments, but are angularly disposed in respect of the axis of the filaments.

Such a macrostructure causes an entanglement of the fibrils which considerably increases the cohesion of the filaments of this invention.

It is this new structure which is responsible for the superior and unexpected properties of the alkali resistant filaments D, E and F of the present invention, and, in particular, for the relatively high elongation at rupture and the relatively high tenacity, and therefore for the considerable improvement of work to rupture. This new structure is also the reason for the high wet tensile strength, the high wet modulus of elasticity, as well as the high resistance to fibrillation.

FIG. 2 (D) illustrates comparatively the known structure of the cottom filament with the spiral arrangement of the fibrils relative to the axis. It is clear from FIGS. 2 (A), 2 (B), 2 (C), 2 (C'), 2 (C") and 2 (D) that the fibrillary structure of the filaments of Group III is much closer to the structure of cotton than the structure of the filaments of Group I and Group [I is to cotton.

The photographs of FIGS. 2 (A), (B), (C), (C'), (C") and (D) were taken on filaments of Groups I, II, III and cotton, swollen in percent nitric acid, and then slightly disintegrated by crushing.

The novel filaments produced in accordance with the present invention have a mean orientation angle in the range of 35 47.

The orientation angle may be defined as being the mean angle which results from the mean orientation of the crystallities in the fibrils and from the mean orientation of the fibrils in relation to each other. The orientation angle is usually determined from X-ray diagrams by analysis of the curves which represent the distribution of the energy diffracted along are 002. This orientation may be defined in particular by the angle 2 a, a being the half-maximum angle, that is, the angular length in degrees of the measured interference are at half-maximum intensity, after correction for background intensity. This method is reported, for example, in Physical Methods in Chemical Analysis" by W. G. Berl, Volume l, 1950 Academic Press, incorporated Publishers, New York.

The filaments of group III produced in accordance with the present invention, as well as filaments of groups I and II, were examined in accordance with the method outlined above and the X-ray diagrams obtained from filaments A and C of groups I and [I and from filaments D, E, and F of group III represented in FIG. 3. FIG. 3 shows that the angular length of are 002 increases in the order from the filaments of group I to the filaments of group III, the opening angles 2:, y, z, z and 1" (not represented) corresponding roughly to the angle 20:.

The differences in opening angles x, y, z, z' and z" are more clearly shown when the angle 2a is measured from the photometric curve of intensity of are 002, a being the angular length in degrees of the interference are at half-maximum intensity, as previously described. The range of opening angles for the filaments of Groups I, II and III are illustrated in the following table.

TABLE I Regenerated Cellulose Orientation Alkali resistant filaments angle Group I (incorporating filament A) 20 25' Group II (incorporating filament C) 28 34'' Group III (incorporating filaments D,E,F) 35 47 particular. the inclination of the fibrils in the filaments of groups I, II, III and cotton.

The novel alkali resistant filaments produced in accordance with the present invention in addition to having an orientation angle above 35, also have an organization degree of about 0.42 to about 0.48.

The organization degree is in direct relationship with the sum of the crystalline parts which constitute the filaments and it is related to what is also called the degree of order. There are various methods known to workers in the art for measuring the organization degree of textile materials. The determination of the organization degree of the filaments of groups I, II and III was carried out in accordance with the method of C. Legrand, set forth in Bulletin de Llnstitut Textile de France, N 125, JulyAugust, 1966, pages 519 to 530.

In this method divergent X-rays produced by an X-ray tube fall on to a sample of about 350 mg of compressed fibers (at room hygrometry and temperature) cut to a length of about 30 microns and disposed at a thickness of 2 mm. on a rectangular surface of 24 X 13 mm.. on a rotating plane in the center of a goniometer.

The focalization is produced on a slit of the goniometric circle behind which is disposed a metering head, both the slit and the metering head moving along the goniometric circle at an angular speed which is twice that of the rotating plane which supports the sample of cut fibers.

The organization degree is calculated only in the region of maximum intensity of the curves obtained, that is, at the angle 2:: of 14 26" corresponding to the crystalline zones 101 and 002. These curves are represented in FIG. 4. An approximate measure of the organization degree was obtained from the ratio (C/C D), C being the surface corresponding to the crystalline zones and D the surface corresponding to the amorphous zone. The novel alkali resistant filaments produced in accordance with the present invention are compared below in table II with the filaments of the prior art.

TABLE II Regeneruted Cellulose Organization Alkali resistant filaments degree Group 1 (incorporating filament A) 0.42 0.47 Group II (incorporating filament C) 0.40 (1.42 Group III (incorporating filaments D,E,F) 0.42 0.48

in Table I and Table 11.

TABLE III Orientation angle Organization degree Group I (Incorporating filament A) 0.4" 0.47 Group ll (Incorporating filament C) 28 34 0.40 0 42 TABLE III-Continued Orientation angle Organization degree Group III (ln corporating filaments D,E.,F) 35 47 0.42 0.48

The alkali resistant filaments manufactured prior to the present invention possessed either a high organization degree with a sacrifice of orientation angle, as noted from Filament A of Group I, or a higher orientation angle with a sacrifice of organization degree as noted from Filament C of Group II. Thus, prior to the present invention, i.e., the development of Filaments D, E and F it was impossible to combine both properties at their highest values at the same time in the same filament. In fact, all the important properties of cellulose regenerated filaments, for example, tenacity, elongation modulus, work to rupture, fibrillation resistance, loop strength, resistance to strong alkalis, dye affinity, etc., depend either from the organization degree or from the orientation angle or from both at the same time. The well defined fibrils of a high degree of organization, which are also strongly inclined in relation to the axis of the filaments, appear to be the fundamental basis for the higher mechanical and technological properties of the new alkali resistant filaments of the present invention.

FIG. 5a and 5b are tenacity-elongation curves illustrating the advantages of the alkali resistant filaments produced in accordance with present invention over those produced in the prior art. FIG. 5a specifically illustrates conditioned elongation curves. FIG. 5b specifically illustrates wet elongation curves.

The alkali resistant filaments of this invention, which have a conditional tenacity of at least about 3.5 g/den., and at the same time, a conditional elongation of at least 14 percent are compared below in Table lv with the filaments of the prior art.

Table IV shows that the filaments of the present invention can be produced in different ranges of tenacity and elongation. Conditioned tenacity may rise from 3.5 to 7 g/den. while the corresponding conditioned elongation decreases from 30 to 14 percent. This combined level of conditioned tenacity and conditioned elongation for the filaments of the invention (Group III) is much higher. as will be shown later, than that of filaments of GROUPS l and 11.

With respect to the high wet tenacity and wet elongation of the alkali resistant filaments produced in accordance with the present invention, reference is made to Table V below, wherein the filaments of the present invention are compared with the prior art filaments.

about 3.5 7 g/den. and ranges of conditioned elongation of about 40-l4 percent which are especially valuable for commercial textiles uses.

TABLE V w w rod t V In in he Alkali resistant filaments Wet Tenacity Wet 5 In i i VI belo the ork p uc a es g/den. Ebngan-on conditloned and the wet states are compared for filament A of Group I, filament B of GRoup II (Normal),

filament C of Group II (improved) and novel alkali re- GROUP l m a very high em ststant filaments D, E and F of Group III (present incity and a very low elongation 3 8.6 9.6 5 l VenliDn).

w I It is clearly seen from FIGS. a and 5b that the areas Filaments with lower tenacity and highe, elongation 2,2 4,7 16 7 llmlted by the curves, by the x axis and by the perpen- RO P m diculars from the ends of the curves to the x axis, are 5 much greater for Filaments D, E and F of the present Filaments of the present I invcmion 23 6 16 invention, when compared with Filaments A, B and C of the prior art.

TABLE VI Conditioned State Wet State Group I Work Product Work Product In general 9O 20 77 Filament A 42 39 Group II In general 45 75 3O 70 Filament B(Group ll normal) 45.5 39 Filament C(Group ll improved) 67 58 Group III (filaments of the present invention) In general 70 I I5 70 llS Filamcnt D 102 9 .5 Filament E 9| 92 Filament F I14 I ll Table V shows equally that the wet tenacity of the al' kali resistant filaments of the present invention may rise from 2.7 to 6 g/den. while the corresponding wet elongation decreases from 40 to 16 percent. This combined level of wet tenacity and wet elongation for the filaments of the present invention (GROUP III) is much higher, as will be shown later, than that of filaments of GROUPS I and II.

The work to rupture" value of textile filaments is an extremely important parameter from an industrial standpoint and it is much more representative than the individual factors of tenacity or elongation to rupture, that is the work to rupture value represents the work that can be done by the filament, the stresses that it can withstand during its passage through textile machinery, the resistance the filament has to fatigue and wear.

The work to rupture value of textile filaments is a function of the area covered by their load-elongation diagram. As the tenacity-elongation curves have the form of a very flattened letter S, or the form of a flattened arc, the areas in question can, in general, be equated to right triangles and therefore the area is roughly half the product of tenscity multiplied by elongation. Therefore, tenacity multiplied by elongation is proportionally an approximate measure of work to rupture. When the wet, respectively the conditioned tenacity in g/den. is multiplied by the wet, respectively the conditioned elongation percent of the filaments of the present invention, there is obtained a figure which is called the work product" which extends from about 70 to about 115 in ranges of conditioned tenacity of Table VI shows also that the filaments of the present invention have a work product that is very high as compared to other prior art alkali-resistant filaments, both in the conditional and wet states.

In addition, it should be emphasized that the filaments of the present invention, even in the already known ranges or work product, have tenacities and elongation characteristics in an entirely new and much more advantageous area, unknown for the filaments of the prior art.

FIG. 6 illustrates the wet elongation under a load of 0.5 g/den. of the filaments D, G and F of the invention (Group III) after treatment with a 5 percent caustic soda solution at 20 C. for 15 minutes. This wet elongation is conventionally considered as a modulus of elasticity".

FIG. 6 illustrates equally the wet elongation under a load of 0.5 g/den. for filament A of Group I, filament C of Group II and on the other hand for a rayon tire filament, and for a so-called high wet modulus H W M filament after treatment of these filaments with a 5 percent caustic soda solution at 20 C for 15 minutes.

FIG. 6 shows a wet modulus of elasticity (after treatment with a 5 percent NaOH solution) of 7 for filament F, 5.5 for filament G and 3.2 for filament D, all of Group II], and a wet modulus of elasticity of 2.5 for a filament of Group I and 5 for a filament of Group II normal.

It is clear, consequently, that all alkali resistant filaments of Groups I, II and [II have a relatively high modulus of elasticity always lower than 8 while the rayon tire filament has a modulus of 20 and the so-called H W M filament a modulus of about l5, that is a very low modulus of elasticity. The corresponding modulus of an ordinary rayon filament is even higher than 20.

Another outstanding characteristic of the alkali resistant filaments produced in accordance with the present invention is the loop tenacity which in the conditioned state is above 1.2 g/den. and generally about 1.2 2.1 g/den.

Further, the fact that the alkali resistant filaments of the invention have simultaneously in the conditioned state a loop tenacity of l .2 2.1 g/den. and an elongation of 14.30 percent, is one of the most distinguishing properties of the filaments of the present invention.

The loop tenacity in g/den. in the conditioned state for filaments of Groups I, II and III is illustrated below:

TABLE VII Alkali resistant filaments Loop Tenacity Group I (Filament A) 0.8 Group II [Filament C) 0.9 1.1 Group 111 (Filament D) 1.4 (Filament E) 1.7 (Filament F) 2.1

It is highly unexpected therefore that the alkali resistant filaments of this invention could possess an excellent loop tenacity and good elongation and at the same time have a high organization degree.

It is indicated at this point that the loop tenacities indicated in this application are calculated from the ratio:

[tenacity at rupture of the loop (g/den.) ]/[2 X titer (den.)] and not, as this appears sometimes in the literature from the ratio:

[tenacity at rupture of the loop (g/den.) ]8c /Titer (den.)

The tendency to fibrillation was examined by subjecting a mixture of 2 grams of product and 200 cc water to vigorous beating in a Knapp Monarch mixer furnished with a rotary blade turning at the rate of 12,000 rpms. The 18 minute treatment in the mixer causes some beginning of fibrillation on the filament D of the present invention, as shown in FIG. 7C and no fibrillation on filaments E and F as shown in FIGS. 7D and E whereas known alkali resistant filaments show numerous fibrils as clearly shown in FIGS. 7A and 7B. 1f the time of treatment is doubled, that is, from 18 to 36 minutes, it is observed from FIG. 7 C' that part of the filament D of this invention presents some longer fibrils and from FIGS. 7 D and 7 E that filaments E and F are practically not fibrillated, while on the alkali resistant filaments of the prior art, fibrillation is very pronounced, as clearly shown in FIGS. 7 A and 7 B.

The fibrillation resistance may be evaluated more specifically by determining the water filtration number of alkali resistant filaments which have been submitted to vigorous beating, in accordance with the method which is described by Battista, Howsmon and Coppick in Industrial and Engineering Chemistry, Volume 45, page 2,107, September, 1953.

In carrying out this method a dispersion of 4 grams of the beaten filaments in 180 cub cm. of water is filtrated under a vacuum upon a fritted glass filter having a diameter of 32 mm. A cake of beaten filaments forms on the surface of the glass filter and an additional quantity of 100 cu. cm. of water is poured over the cake of beaten filaments and filtered under a vacuum. The water filtration number is the time in seconds which is required for the 100 cu. cm. of water to filtrate completely through the cake of beaten filaments. Therefore, the water filtrates all the more slowly when the filaments are more fibrillated. The water filtration numbers which were obtained from the filaments of Groups I, II and III are reproduced in Table VIII below:

TABLE VIII Alkali resistant filaments Water filtration number Group I (Filament A) Group II (Filament C) 20 Group III (Filament D) B 10 (Filament E] 5 6 (Filament F) 4 Filaments/Bath Ratio 1/75 (Weight ratio between the filaments and the bath) 1.5% In relation to the weight of the filaments.

Concentration of Dye Concentration of Electrolyte 50 N11 50% In relation to the weight of the filaments. C.

Temperature The dyeing index is expressed by the weight ratio: [Dye picked up by the filaments/Dye present initially in the bath](Expressed in a percentage). The following Table gives the percentage of the dye which is picked up by filaments of Groups I, II and III at different time intervals within 5 hours.

TABLE IX Dyeing Time qr of Dye fixed on the filaments GROUP 1 GROUP 11 GROUP 111 (Filament D, E, and F) 5 minutes 0.21 0.8 0.9 l 15 minutes 0.36 1 1,1 1.2 30 minutes (dyeing index) 0.50 1.10 1.15 1 hour 080 1,18 1.25 1.30 2 hours 1.05 1.30 1.30 5 hours 1.3 1.38 1.35

Table IX illustrates that the dyeing index of filaments of Group III is much higher than the dyeing index of filaments of Group I while it is nearly equal to that of filaments of Group II. For higher dyeing times, as is well known, the differences become smaller and finally after about 5 hours they disappear almost completely. lnversely, after 5 minutes of dyeing time, which is a very shor period, the differences are more pronounced. However, after about 30 minutes, which approaches dyeing time on an industrial scale, the filaments of Group 111 show a specifically higher dyeing index than that displayed by the filaments of Group 1. Even though the filaments of Group 11 display a dyeing index after 30 minutes of 1.10 these filaments have a lower orientation angle, a lower organization degree, and conse- 13 14 quently inferior mechanical properties, in comparison TABLE XII with filaments of Group III.

The novel alkali resistant filaments of the present inmm c ditioned 16.] vention can be made into fabrics which have an excel- E i F C d :52 lent ability to take wash and wear treatments. No. 70 8253582 metric yarns with a torsion of 830 turns per meter were Lea Test 2500 prepared from 1.5 denier filaments of groups I, II and III (Filament D) cut to a length of 40 mm. and from h h h H F cotton. The mechanical properties of the spun yarns Table 5 CW5 t at t e Spun m F g which were obtained are listed below in Table x. I has equally va'uable pfopert'es P t e e field, 1n particular where h1gh elongation combined TABLE x with relatively high tenacities are required. pmpenies of N0 70 Metric Yams Furthermore, no. 30 metric yarns were prepared from 2.2 den acetylated filaments D (to be described GROUP GROUP GROUP 15 later in example 17) cut to a length of 40 mm.

Improved (Present Yarn invention) The mechanical properties of the spun yarns which (Filgment were obtained are enumerated below in table XIII, in comparison with the properties of the corresponding RKm" spun yarn from triacetate filament described as well in conditioned 18.9 l9.l 27.5 l4.l x m 7 RKm wet l4.6 14.8 22.3 17.9 20 e a P6 1 Elongation conditioned 7.7 8 9.9 6.8 TABLE XI" Elongation wet 7.8 12.5 7.7 L est 2900 2800 3930 2220 Properties of no. 30 metric yarn Length of rupture in kilometers. From From Filamaent D Triacetate Poplin fabrics were woven from the spun yarns described above and the fabrics were then subjected to a 2%: f 'z i g": permanent press treatment (Koratron type) whereupon Elongation, conditioned, 9.4 13

Elongation, wet I l .7 2L3 the fabncs displayed the propert1es shown below m Lea Test 2438 928 Table XI.

TABLE XI GROUP I GROUP II GROUP III COTTON Improved (Present) Invention) (Filament D) Weight per meter. g. H2 113 ll2 lll Count numbers per cm. 47 X 28 47 X 2B 47 X 28 47 X 28 Wash and Wear Index" 3 4 3 4 3 4 3 4 Conditioned strength: filling. Kg. 28 28 38 I8 Tcar strength. filling. Kg. 1.1 1.3 1.9 0.4 Stall-flex Abrasion cycles I30 I I0 275 I80 Monsanto Method AAICC 4965 No. 88A I964 The results obtained in Table XI, more specifically the conditioned strength, tear strength and abrasion, have been further emphasized by setting forth the re- Plain fabrics were woven from 30/2 ply yarns described above whereupon the fabrics displayed these properties shown in Table XIV.

sults obtained from Table XI in FIG. 8. It is clearly evi- 6O dent from FIG. 8 that the fabric of the present invention prepared from the filament D of Group III displays an unexpected ability to withstand wash and wear treatments as compared to fabrics prepared from filaments of Groups I, II and cotton.

Furthermore, a no. metric yarn with a torsion of 760 turns per meter was prepared from 3 den. filament F of Group III cut to a length of 40 mm.

The mechanical properties of the spun yarns which were obtained are listed below in Table XII.

It is evident from Table XIV that the fabrics from the acetylated filaments of the present invention have far superior general properties when compared to corresponding fabrics from usual triacetate filaments.

The following are illustrative of the novel combination of steps for carrying out the process of the present invention for producing the noval alkali resistant filaments described herein above.

I. A viscose having a gamma index between and I00, a viscosity greater than 300 poises and preferably greater than 500 poises, containing a cellulose whose DP is above 400.

II. A dilute acid bath having a temperature below 40C., containing less than g. per liter sulfuric acid, sodium sulfate, and small quantities of zinc sulfate, i.e., less than 2 g per liter. At the time of spinning the bath should not decompose more than percent of the xanthate groups which are initially present in the viscose.

III. A vertical or horizontal spinning device with or without tube can advantageously be used, for example, the device described in US. Pat. No. 3,139,467, whereby vertically spun filaments which are too weak to support themselves, are supported from the time of emergence from the bath by a partially submerged roll on which they arrive tangentially.

lV. One of the essential characteristics of the process for preparing the novel alkali resistant filaments of this invention is the formation of a gel that simultaneously exhibits very exact physical and chemical characteristics (the term gel" as used herein is to be understood to define freshly spun filaments in a state of partial regeneration). These characteristics are: gamma index, acidity, and swelling, and must be within a specific range. Furthermore, each of the said characteristics must have a specific value in its ownrange so that the claimed results may be obtained. In other words, there must be an interdependence between the said three parameters and any variation of one of the parameters in its own range immediately affects the other parameters. If these conditions are not observed, only medium quality alkali resistant filaments will be obtained with a work product, for example, which may be 30 percent lower. The gel is obtained by subjecting the freshly spun filaments upon their emergence from the first dilute bath and while they have a gamma index 45, to a friction stretching on fixed guides (first stretching operation), which causes a rapid elimination of the acid that impregnates the filaments. At this time, the filaments (designated simply by the expression the gel") must have the following characteristics:

a. The gel must contain a cellulose xanthate with a specific gamma index whose 'y 1 value lies between 28 and 40, preferably between 32 and 36, that is l) (the gamma index as is known represents the number of CS molecules fixed on lOO glucose units) b. The gel must have a low degree of swelling (near to the limit degree of swelling) in order to have a homogeneous composition. It should have a degree of swelling G ranging between 5 and 8, preferably of the order of 6, that is (the gel swelling represents, in fact, the ratio between the weight of centrifuged gel (G 300) and the weight of cellulose contained in said gel).

c. The liquid impregnating the gel should have an acid concentration a in grams liters between 6 and 9.5, preferably between 7.5 and 8, that is V. Another novel step of the process for preparing the novel alkali resistant filaments of this invention is the stretching of said obtained filaments in air. This second stretching operation is of the order of 0 to percent and there is at this stage a decomposition of part of the residual xanthate groups under the effect of the acid contained in the liquid impregnating the gel.

Moreover, this second stretching operation is completely distinct and separate from the first stretching operation and makes it possible to produce alkali resistant filaments having mechanical properties varying in a wide range, extending for instance from 2.7 to 6 g/den. for tenacity in the wet state and from 40 to 16 percent for the corresponding elongation.

But all the alkali resistant filaments obtained, independently from the importance of the second stretching, have the same type of structure and keep a high work product. This emphasizes the wide reaching importance and unobvious nature of the new process of the invention.

Vl. Still another important characteristic of the process of the present invention is the fact that the filaments in the gel state after the stretching in air, have a residual gamma index 7-, between 18 and 28, preferably between 21 and 25 that is It is important that the quantity of free acid contained in the gel be sufficient to cause complete decomposition of the cellulose xanthate at the moment of stretching.

A stoichiometric computation makes it possible to establish with sufficient precision that:

Since y must be between 18 and 28 according to formula (4) above, there must be then:

Formula (6) expresses another essential condition of the invention. In other words, 7,, G and a must not only satisfy formulaes l (2) and (3), but also formula (6).

Thus if 'y, 35, G 6 and a 7.5, formula (5) yields 72 22.5, which is well within the range of 18 to 28. The necessary condition of the process will be obtained.

If, on the other hand, 1, =29, G 7 and a 8, formula (5) yields ya 13. This does not meet the conditions of the process because formula (6) is not complied with.

It, therefore, is clearly evident that there must be a certain equilibrium between 7 a and G if formula (6) is to be verified. For example, when 1 is increased, a or G must be increased, or both a and G, so that y, will remain at the desired value.

Vll. A further characteristic of the process for preparing the novel alkali resistant filaments of the present invention is the relaxation of the filaments in a bath which contains less than 2 grams per liter sulfuric acid.

This relaxation is effected in a dilute acid bath whose temperature is between 20 and 80C. This relaxation further improves the excellent transverse characteristics of the initial gel filaments having determined gamma index, acidity, and swelling degree, and it gives rise to high loop strength and excellent fibrillation resistance of the filaments, This relaxation should be varied according to the physicomechanical properties desired of the filaments produced in accordance with this invention. The relaxation should be approximately 8 to 10 20 percent. After relaxation, the gamma index of the filaments will be between 14 and 6. Finally, regeneration of the filaments is accomplished in a third bath containing a dilute hot acid.

The invention will be further described by means of 15 the following specific examples which are given for illustration only, and are not to be taken as in any way limiting the invention beyond the scope of the appended claims.

EXAMPLE 1 A sulfate pulp having a DP of 760 to 780 and containing 98 percent alpha cellulose was immersed in 240 g/liter caustic soda lye at 18C. for 30 minutes, and

then pressed to the ratio of 2.87 in proportion to alpha cellulose. The alkali cellulose thus formed was crumbed in a Werner schredder for 45 minutes, and then aged at 32C. for 4 to 5 hours. This alkali cellulose was then xanthated with 55 percent carbon disulfide (in proportion to the alpha cellulose) in a churn at 22C. for 5 hours and the resulting cellulose xanthate was then introduced into a mixer with water and a soda solution to be converted into a viacose containing 5.5

percent cellulose of DP 600 and 3.4 percent soda, 35

with a viscosity between 550 and 600 poises, and a gamma index of 76 in final solution. This viscose additionally contained 25 ppm of gluconic acid (a complexing agent) and 0.1 percent liter of an antifoaming agent such as isodocanol.

This viscose was spun in a first bath containing 15 g/Iiter sulfuric acid, 52 g/liter sodium sulfate, 0.3 g/liter zinc sulfate and 0.03 g/liter of an anionic agent (sodium alkylarylsulfonate, imparting a surface tension of 32 dynes/cm2 to the bath) at a temperature of 25C., using tangentially by a roll semi-submerged in the bath, which carried the filaments slowly out of the bath. When they had traveled a certain distance on the external part of the roll, coagulation had progressed suffciently and the filaments then had sufficient strength to sustain themselves in the air and to be able to be subjected to the first stretching operation. The vertical spinning device used was substantially the same as that described in US. Pat. No. 3,139,467. The gamma index of the filaments as they emerged from the bath was of the order of 50.

The filaments then passed on fixed guides through a series of sharp angles and along a louvered path while they were subjected to a first stretching which had the effect of squeezing off the adhering acid liquid, thereby totally removing the entrained bath liquid. The liquid subsequently expressed from the filaments was thus derived practically from the interior of the filaments. At the level of the last guide element, the liquid had an acid content of 7.5 g/liter. At the same level, the filaments in the gel state had a gamma index of 34 and a gel swelling of 6.

The filaments without adhering liquid, i.e., expressed gel filaments, were then subjected in air, and without the action of any outside liquid, to a second percent stretching operation which brought the total stretch to 188 percent. At the end of the stretching operation, because of the acidity and the gel swelling previously described, the residual gamma index still was 22, so that the conditions of formulaes (1), (2), (3) and (6) were fulfilled. The filaments were then relaxed between two sets of rollers in a 20 C. bath containing 0.5 g/liter sulfuric acid, so that during this operation they retracted by 12 percent. Upon emergence from the relaxation bath, the gamma index was 12. Finally, regeneration was accomplished in a C. bath containing 10 g. sulfuric acid and 20 g. sodium sulfate per liter. The speed of the filaments at the end of the spinning machine was 20 m/min.

After the usual finishing treatments, the filaments which were obtained presented the characteristics indicated in Table XV below.

In comparison, there are indicated in Table XV the characteristics of a filament of Group 1 (high tenacity and very low elongation Filament A), of a filament of Group [1 Normal (low tenacity and high elongation Filament B), of a filament of Group 11 Improved (Filament C) and of a filament of the present invention obtained in accordance with Example 1 (Filament D 50 Group 111).

19 20 A L XV -Continued GROUP 1 GROUP ll GROUP ll GROUP lll Normal improved Filament of the present invention Filament A Filament B Filament C Filament D Wet Modulus after action of 55% NaOH [elongation "/1 under a load of 0.5 g/den.) L6 4 3.7 3.l Orientation angle 22 30 32 42 Organization degree 0.47 0.40 0.42 0.48 Water filtration number 70 20 20 Dyeing index 0.5 L2 1.] l.l5

Table XV clearly shows the important characteristics of the filaments of the present invention from the point of view of the work product, as well as from the point of view of tenacity, elongation, modulus of elasticity, loop tenacity, and resistance to 5 percent soda solutions.

All characteristics of tenacity and elongation at break given in Table XV and throughout this disclosure were determined according to the well known rules of B.l.S.F.A. (Bureau International pour la Standardisation des Fibres Artificielles).

Moreover, it is already apparent from Table X that the novel alkali resistant filaments of the present invention make it possible to obtain yarns that not only in the conditioned state, but also in the wet state, have characteristics of tenacity and elongation which are superior to those of corresponding combed American cotton yarns.

The excellent general properties of the filaments of the invention are also evident at all stages subsequent to spinning, especially in sizing, weaving, bleaching, finishing, etc.

The ability of these fibers to take wash and wear treatments of the Koratron type, for example, is excellent. After this treatment breaking load and abrasion resistance are considerably higher for fabrics made from the described filaments in comparison to fabrics made from filaments of Group I, Group ll and cotton as more fully illustrated in FIG. 8. These results show that filament D is particularly suitable for blending with cotton.

EXAMPLE 2 Exactly the same viscose was used as described in Example 1, and spinning was carried out in a bath containing 17.5 g/liter sulfuric acid, 50 g/liter sodium sulfate, 0.3 g/liter zinc sulfate, and 0.03 g/liter of an anionic agent, i.e., sodium alkylarysulfonate (which imparted a surface tension of 32 dyneslsqcm. to the bath) at a temperature of 24 C., using a spinneret with 6,600 orifices 7/100 mm in diameter. The filaments were spun vertically without a tube, passed through the bath over a path cm in length, and at the point of emergence, they were taken up tangentially by a semisubmerged roll that carried the filaments out of the bath, as in Example 1. After having traveled a certain distance on the outer part of the roll, the filaments were subjected to a first 45 percent stretching but they did not pass on fixed guides along a louvered path as in Example I. In these conditions, the first stretching brought about a much lower decrease of liquid content in comparison to that of Example 1, and because of this, the liquid extracted from the filaments and collected immediatly after the first stretching had an acid content of 10 g/liter. At this level, the filaments had a gamma index of 30 and a gel swelling of 7.

The slightly expressed gel filaments were then subjected to a supplementary stretch of percent, in air, without undergoing the action of any external liquid, which brought the total stretching up to 146 percent. At the end of the stretching, the filaments had a residual gamma index of 10. The filaments were then relaxed with no tension in a 20C. bath that contained 0.5 g/liter sulfuric acid. During this operation, the filaments underwent a maximum retraction of 6 percent; upon emerging from the relaxation bath, the gamma index was 3. The filaments were finally passed into a regenerating bath which had the same composition and temperature as in Example 1. The speed of the filaments bundle at the end of the spinning machine was 20 meters per minute.

After the usual finishing treatments, a filament bundle was obtained which had the following characteristics:

Total denier 9900 Filament denier l.5 Tenacity (conditioned)gpd S Elongation (conditioned)% ll Tenacity (wet) gpd 4 Elongation (wet) l2.5 Loop Tenacity g/den (conditioned) 0.9 Work Product (conditioned) 55 Work Product (wet) 50 Orientation angle 28 Organization degree 0.47 Water filtration number 35 Dyeing index 0.6

The relatively poor qualities of the filaments obtained in Example 2 are clearly due to the fact that the values of a, and 7, did not satisfy the limit requirements of formulae (3), (4) and (6).

EXAMPLES 3 to 8 The viscose of Example I was spun in the same bath and under the same conditions as described in Example 1, with the exception that the first stretching and more particularly the second stretching ope ration was varied.

The filaments were spun vertically without a tube, passed through the bath over a path 20 cm in length, and, at the point of emergence, while they were still incapable of supporting themselves, they were taken up tangentially by a roll semi-submerged in the bath, which carried the filaments slowly out of the bath.

When they had traveled a certain distance on the external part of the roll, coagulation had progressed sufficiently, and the filaments then had sufficient strength to sustain themselves in the air and to be able to be sub- TABLE XVI Group 111, Filaments of the present invention.

Example 4 5 3 6 7 l 8 Filament Reference F G H E 1 D J First Stretching 60 6O 45 Second Stretching 0 7 l 1.2 38 60 Total Stretching 45 60 80 180 Titer, den. 3 2.7 2.4 2 1.6 1.5 1.5 Tenacity g/den. 3.8 4.2 4.7 5.1 5.8 6.2 6.5 (Conditioned) Elongation 7? 3O 26 21 18 17.5 16.6 14.5 (Conditioned) Wet tenacity g/den. 2.8 3.2 3.6 4.2 4.6 5 55 Wet elongation ll 40 33 27 22 19 18.2 16 Work Product (tenacity X elon ation) Con itioned 114 109 98 91 101 102 94 Wet l 12 105 97 92 87 90 88 Loop tenacit g/den. (conditioned) 2.1 [.8 l 7 l 7 1.6 l 4 l 2 Wet Modulus (elongation '7 under a load of 0.5 g/dcn.) 4.5 3.7 3 2 2 8 2.4 2 2 l 8 Wet Modulus after action of 59% NaOH (elongation Fl under a load of 0.5

g/den.) 7 5 5 4.7 3.9 3.4 3.1 2.9 Orientation angle 47 45 43 42 37 Organization degree 0.42 0.43 0.40 0.48 0.48 Water filtration numher 3 4 6 l0 l0 l0 Dycingindcx 1.2 1.15 1.15 1.1 l.l5 1.1 1.1

45 percent first stretching operation which had the ef- 45 feet of squeezing off the adhering acid liquid, thereby totally removing the entrained bath liquid. The liquid subsequently expressed from the filaments was thus derived practically from the interior of the filaments. As

the level of the last guide element, the liquid had an 50 acid content of 7 7.5 g/liter. At the same level, the filaments in the gel state had a gamma index of 33 35 and a gel swelling of 6 6.5.

The filaments without adhering liquid, i.e. expressed gel filaments, were then subjected in air, and without 55 the action of any outside liquid, respectively to a second 0, 7, l 1.2, 38, 60, and 90 percent stretching operation, so that the total stretch was respectively 45, 60, 80, 120, 165 and 175 percent. At the end ofthis second stretching operation the gamma index 7 of the fila- 6o ments was comprised between 18 and 22.

After this second stretching operation the filaments were relaxed from 1 l to 12 percent in a 20C. bath containing 0.5 g/liter sulfuric acid and then regeneration was accomplished in a 95C. bath containing 10 g sulfu- 65 ric acid and 20 g sodium sulfate per liter.

The final speed of the filaments at the end of the spinning machine was respectively of 10, l 1.1, 12.5, 15.2, 18.4 and 19 meters per minute.

Table XVI clearly shows the wide range of properties, in particular of elongation and loop tenacity of the alkali resistant filaments of the present invention, which nevertheless have all a high work product, a relatively high wet modulus and an excellent resistance to fibrillation.

It is equally apparent from Table XVl that the fibers from filaments D, E, F, G, H, l, and .1 of the present invention are highly suitable for blends either with a variety of snythetic fibers or wool,, or cotton, since they have tenacity and elongation properties which spread over a very large area, the loop tenacity remaining always at a high level.

EXAMPLES 9 to 12 A sulfate pulp having a DP of 760 to 780 and containing 98 percent alpha cellulose was immersed in 240 g/liter caustic soda lye at 18C. for 30 minutes, and then pressed to the ratio of 2.87 in proportion to alpha cellulose. The alkali cellulose thus formed was crumbed in a Werner schredder for 45 minutes, and then aged at 32 C. for 4 to 5 hours. This alkali cellulose was then xanthated with 55 percent carbon disulfide (in proportion to the alpha cellulose) in a churn at 22C. for 5 hours and then introduced into a mixer with water and a soda solution to be converted into a viscose containing 6.2 percent cellulose of DP 600 and 3.5 percent caustic soda, with a viscosity of 900 poises, and a gamma index of 77 in final solution. This viscose additionally contained 25 ppm of gluconic acid (a complexing agent) and 0.1 percent of an antifoaming agent such as isodecanol. 

1. AN ALKALI RESISTANT REGENERATED CELLULOSE FILAMENT, HAVE AN ELONGATION IN THE WET STATE LOWER THAN 8 PERCENT UNDER A LOAD OF 0.5 G/DEN. AFTER TREATMENT WITH A 5% CAUSTIC SODA SOLUTION AT 20*C. FOR 15 MINUTES, SAID FILAMENT HAVING AN ORIENTATION ANGEL OF ABOUT 35* TO ABOUT 47* AND AN ORGANIZATION DEGREE OF ABOUT 35* TO ABOUT 0.48 AND FURTHER HAVING PRIOR TO ANY TREATMENT WITH AN ALKALINE SWELLING AGENT A CONDITIONED TENACITY OF ABOUT 3.5 - 7 G/DEN., A WET TENACITY OF ABOUT 2.7 - 6 G/DEN. AND A WORK PRODUCT BOTH IN THE CONDITIONED AND WET STATE OF ABOUT 70 -
 115. 2. An alkali resistant regenerated cellulose filament having the following characteristics:
 2. a conditioned elongation of about 14 - 30 percent;
 3. a wet elongation of about 16 - 40 percent;
 3. The alkali resistant regenerated cellulose filament of claim 2 further characterized in being substantially non-fibrillatable and having a water filtration number of about 3 to about
 10. 4. The alkali resistant regenerated cellulose filament of claim 2 having prior to any treatment with an alkaline swelling agent a conditioned tenacity of about 3.5 - 7 g/den., a wet tenacity of about 2.7 - 6 g/den. and a work product both in the conditioned and wet state of about 70 -
 115. 4. an orientation angle of about 35* to about 47*;
 5. an organization degree of 0.42 to about 0.48;
 5. The alkali resistant regenerated cellulose filament of claim 2 further characterized in being substantially non-fibrillatable and having a water filtration number of about 3 to about
 10. 6. a conditioned loop tenacity of about 1.2 - 2.1 g/den. prior to any treatment with an alkaline swelling agent;
 7. a conditioned tenacity of about 3.5 - 7 g/den. prior to any treatment with an alkaline swelling agent;
 8. a wet tenacity of about 2.7 - 6 g/den.; and
 9. a work product both in the conditioned and wet state of about 70 -
 115. 